I went to Great Plains Audio this weekend with a pair or Altec 605B's that I opened up a thread on earlier. I had them do a complete refurb.
1) re-magnetization
2) re-coning
3) new horn transducers
4) 200 watt voice coil upgrade
5) conversion to 8 ohms from 16 ohms

Both speakers worked fine going in and the condition of these speakers is as good as I've ever seen for an Altec speaker:
Front View
Back View
Side View

Anyway I met Bill, Rusty and Carlotta?.
They are a great crew and they were just exceptionally nice. They took time out to show me the old tools and dies that they use to restore these speakers and horns. They seem to love what they do and I think we owe them a debt of gratitude for continuing to support the Altec legacy.

I also learned several things in conversation that I think should be documented here:
1) The difference between the 604A and the 605B has to do with the surround of the woofer. The 605A had a pressed paper surround and the 605B had a cloth surround.
2) The Manta Ray horn versus the multi-cellular design. The Altec engineers tested the supposed "lobing" effect of the multi-cellar horn and found nothing to indicate this was true.
3) The difference between the 604E and the 605B. The 604E has a larger magnet structure and that is it. Not many 605B's were made. Nothing new here but the smaller magnet structure lowers the Q thereby offering a little lower bass response.
Albeit not as sensitive as the 604E, but with the advances in amplification...who cares?
4) I saw some prototypes of the new speakers Bill is working on. One is a reproduction of the famous guitar 12" speakers Altec used to make. They were the bomb as replacements for Fender Twin and Mesa Boogie amps. I can hardly wait!